The present disclosure relates to an air conditioner.
Air conditioners are appliances that maintain air within a predetermined space to the most proper state according to use and purpose thereof. In general, such an air conditioner includes a compressor, a condenser, an expansion device, and an evaporator. Thus, the air conditioner has a refrigerant cycle in which compression, condensation, expansion, and evaporation processes of a refrigerant are performed. Thus, the air conditioner may heat or cool a predetermined space.
The predetermined space may be variously provided according to a place at which the air conditioner is used. For example, when the air conditioner is disposed in a home or office, the predetermined space may be an indoor space of a house or building. On the other hand, when the air conditioner is disposed in a vehicle, the predetermined space may be a boarding space in which a person is boarded.
When the air conditioner performs a cooling operation, an outdoor heat-exchanger provided in an outdoor unit may serve as a condenser, and an indoor heat-exchanger provided in an indoor unit may serve as an evaporator. On the other hand, when the air conditioner performs a heating operation, the indoor heat-exchanger may serve as the condenser, and the outdoor heat-exchanger may serve as the evaporator.
FIG. 1 is a view illustrating a distributor and a variation in velocity of wind passing through a heat exchanger according to a related art.
Referring to FIG. 1(a), a heat exchanger 1 according to the related art includes a plurality of refrigerant tubes 2 arranged in a plurality of rows, a coupling plate 3 coupled to ends of the refrigerant tubes 2 to support the refrigerant tubes 2, and a header 4 for dividing a refrigerant to flow into the refrigerant tubes 2 or mixing the refrigerant passing through the refrigerant tubes 2.
The header 4 extends in a length direction along the arranged direction of the refrigerant tubes 2. For example, as illustrated in FIG. 1, the header 4 may extend vertically.
The heat exchanger 1 further includes a distributor 6. The distributor 6 may divide the refrigerant introduced into the heat exchanger 1 to flow into the plurality of refrigerant tubes 2 through a plurality of branch tubes 5 or mix the refrigerants passing through the plurality of refrigerant tubes 2 with each other through the plurality of branch tubes 5.
Each of the branch tubes 5 may include a capillary tube.
The heat exchanger 1 further includes a distributor connection tube 7 for introducing the refrigerant into the distributor 6 and an inlet/outlet tube 8 for guiding the refrigerant into or out of the heat exchanger 1.
In the above-described heat exchanger 1, the refrigerant may flow in directions opposite to each other when the cooling or heating operations are performed. Hereinafter, a case in which the heat exchanger 1 is an “outdoor heat exchanger” will be described as an example.
When the air conditioner performs the cooling operation, the outdoor heat exchanger 1 may serve as a condenser. In detail, the high-pressure refrigerant compressed in the compressor is introduced into the header 4 and then divided to flow into the plurality of refrigerant tubes 2. Then, the refrigerant is heat-exchanged with outdoor air while flowing into the plurality of refrigerant tubes 2. The heat-exchanged refrigerants are mixed with each other in the distributor 6 via the plurality of branch tubes 5 to flow into the indoor unit.
On the other hand, when the air conditioner performs the heating operation, the outdoor heat exchanger 1 may serve as an evaporator. In detail, the refrigerant passing through the indoor unit is introduced into the distributor 6 through the distributor connection tube 7. Also, the refrigerant may be introduced into the refrigerant tube 2 through the plurality of branch tubes 5 connected to the distributor 6, and the refrigerant heat-exchanged with the refrigerant tube 2 may be mixed in the header 4 to flow toward the compressor.
Referring to FIG. 1(b), a variation in speed of wind passing through the outdoor heat exchanger 1 according to positions of the outdoor heat exchanger 1 is illustrated. A blower fan for blowing external air may be disposed on a side of the outdoor heat exchanger 1. The external air passing through the outdoor heat exchanger 1 may vary in wind speed or amount according to installation positions of the blower fan or arrangements of structures around the outdoor heat exchanger.
For example, FIG. 1(b) illustrates a state in which an upper wind speed of the outdoor heat exchanger 1 is greater than a lower wind speed of the outdoor heat exchanger 1. In detail, when the blower fan is disposed at an upper portion of the outdoor heat exchanger 1, a wind speed at a portion of the outdoor heat exchanger 1 that is adjacent to the blower fan, for example, at the upper portion of the outdoor heat exchanger 1, may be greater than that at a lower portion of the outdoor heat exchanger 1.
In this case, the refrigerant of the refrigerant tube 2 disposed in the upper portion of the outdoor heat exchanger 1 may have relatively superior heat-exchange efficiency. However, the refrigerant of the refrigerant tube 2 disposed in the lower portion of the outdoor heat exchanger 1 may be deteriorated in heat-exchange efficiency. To solve the above-described limitation, the branch tube 5 extending toward an upper side of the outdoor heat exchanger 1 may have a length less than that of the branch tube 5 extending toward a lower side of the outdoor heat exchanger 1. In this case, an amount of refrigerant flowing into the branch tube 5 extending toward the upper side of the outdoor heat exchanger 1 may be greater than that of refrigerant flowing into the branch tube 5 extending toward the lower side of the outdoor heat exchanger 1.
As illustrated in FIG. 1, the distributor connection tube 7 according to the related art may have a bent shape to extend upward when being connected to the distributor 6. Also, the distributor 6 is connected to the distributor connection tube 7 to extend upward. The above-described configuration may vary according to installation conditions of the branch tube 5 connected to the heat exchanger 1 from the distributor 6 or interference conditions with other structures of the outdoor unit or indoor unit in which the heat exchanger is installed.
According to the above-described structure, almost identical gravities may be applied to the distributor connection tube 7 and the distributor 6 to prevent the gravity from being differently applied according to the refrigerant paths. Also, the distributor 6 and the distributor connection tube may be designed on the basis of a rated load of the air conditioner. Here, the rated load may be a load corresponding to a rated flow rate of the refrigerant circulated into the air conditioner.
That is, the arrangement of the distributor as illustrated in FIG. 1 may be effective under the rated load condition of the air conditioner.
On the other hand, when the air conditioner operates under conditions different from the rated load condition, for example, when the air conditioner operates under a low load condition that is less than the rated load, and the heat exchanger serves as the evaporator, a deviation in a degree of superheat may significantly occur according to a path of refrigerant introduced into the heat exchanger from the distributor.
In detail, when the air conditioner operates at the rated load, i.e., when the rated flow rate of refrigerant is calculated, an evaporation pressure is relatively low, and humidity of the refrigerant is relatively high. Thus, a flow loss of the refrigerant flowing into the branch tube 5 may be somewhat large.
Thus, a length or position of the path of the refrigerant flowing from the distributor 6 to the heat exchanger 1 may be designed in consideration of the pressure loss. For example, since the path having a relatively large pressure loss has a relatively small refrigerant flow rate, the path is connected to a low-wind speed side of the heat exchanger. Also, since path having a relatively small pressure loss has a relatively large refrigerant flow rate, the path is connected to a high-wind speed side of the heat exchanger.
On the other hand, when the air conditioner operates at a low load that is less than the rated load, i.e., when the refrigerant having a low flow rate that is less than the rated flow rate is circulated, the evaporation pressure may be relatively high, and the humidity of the refrigerant may be relatively low. Thus, the refrigerant flowing into the branch tube 5 may have a relatively lower pressure loss.
In this case, since a difference in refrigerant flow rate of the refrigerant flowing into the plurality of branch tubes 5 is not large, the refrigerant flowing toward the high-wind speed side of the heat exchanger may be excessively heated, or the refrigerant flowing toward the low-wind speed side of the heat exchanger may not be well heated in the case of the design of the distributor and heat exchanger at the rated load.
FIG. 2A illustrates a temperature variation and evaporation temperature at an inlet, a middle portion, and an outlet of the heat exchanger in each path of the heat exchanger when the air conditioner operates at the rated load. The evaporation temperature may be understood as a temperature after the refrigerants of the plurality of paths, which pass through the heat exchanger, are mixed with each other.
Also, FIG. 2B illustrates a temperature variation and evaporation temperature at the inlet, the middle portion, and the outlet of the heat exchanger in each path of the heat exchanger when the air conditioner operates at the low load.
Referring to FIG. 2B, the degree of the superheat may be determined as a difference value between the evaporation temperature and the outlet temperature in each path. In case of the path 5 of the heat exchanger, the degree of superheat is about 5° C. that is a difference value between the outlet temperature (about 24° C.) and the evaporation temperature (about 19° C.) of the heat exchanger. That is, the degree of superheat of path 5 is greater than that (about 1° C. to about 3° C.) of each of the other paths.
Thus, in case of the arrangement of the distributor according to the related art, it is seen that a deviation in degree of superheat in each path of the heat exchanger is significantly large.
As a result, when the air conditioner operates under the conditions other than the rated load condition, such as a low load condition, a deviation in degree of superheat of the refrigerant passing through the heat exchanger may be large, which tends to deteriorate operation performance of the air conditioner.
This limitation may occur where the heat exchanger 1 is the outdoor heat exchanger as well as the indoor heat exchanger that serves as the evaporator according to the operation mode of the air conditioner.